ABSTRACT Cigarette smoking is the leading cause of preventable death in the United States, causing approximately 480,000 smoking-related deaths per year. The Food and Drug Administration (FDA) has the regulatory authority to enact tobacco product standards if such product changes would more likely than not have a positive public health impact. In 2009, the FDA banned flavored cigarettes from being sold but allowed menthol cigarettes to remain on the market. Nearly one-third of the cigarettes sold in the U.S. have menthol as a characterizing flavor, and these cigarettes are associated with low quit rates in vulnerable populations. Survey data suggest that large proportions of menthol cigarette smokers would quit if menthol cigarettes were no longer available. Therefore, tobacco control policies aimed at limiting access to menthol cigarettes may have major public health benefits. However, if menthol cigarettes were no longer available, smokers may switch to flavored little cigars or cigarillos (LCCs) due to their similarities to cigarettes. From a harm reduction perspective, switching to LCCs rather than quitting smoking or using non-combustible tobacco products will not improve individual or population-level health outcomes. Thus, tobacco control policies focusing on menthol cigarettes may need to apply broadly to all combustible tobacco products. Behavioral economics is an ideal framework for addressing this research question because it applies economic constructs such as response cost, product substitution, and demand elasticity to understand product consumption and decision-making. We are proposing a within-subjects laboratory study and followed by validation field assessments to understand how restricting access to menthol cigarettes would affect alternative tobacco product selection and use. We will enroll 40 menthol smokers who will complete four lab sessions and two field assessments. During two of the lab sessions, participants will complete a behavioral economics assessment, the Experimental Tobacco Marketplace task, designed to simulate how restricting access to menthol cigarettes would affect the purchase of alternative products, which will include menthol LCCs in one session but not include menthol LCCs available in another session. After these lab sessions, participants will be provided with the tobacco products they purchased to use during a 3-day field assessment to validate the task. At the final lab session, a qualitative interview with these participants will be conducted to learn more about their experiences selecting and using tobacco products other than menthol cigarettes. Data from this trial will inform public health officials and policy- makers about what types of tobacco products, if any, smokers may select when access to menthol cigarettes is restricted.